1. Technical Field The present invention relates to a common mode filter and a method of manufacturing the same, and more particularly, to a common mode filter having an insulating layer disposed on a side of an element and a method of manufacturing the same.
2. Description of the Related Art
In accordance with the development of a technology, electronic devices such as a portable phone, a home appliance, a personal computer (PC), a personal digital assistant (PDA), a liquid crystal display (LCD), and the like, have been changed from an analog scheme into a digital scheme and have been speeded up due to an increase in a data amount to be processed. Therefore, USB 2.0, USB 3.0, and a high-definition multimedia interface (HDMI) have been widely distributed as a high speed signal transmission interface and used in numerous digital devices, such as a personal computer, a high quality digital television, and the like.
Unlike a single-end transmission system generally used for a long period of time, these interfaces adopt a differential signal system that uses a pair of signal lines to transmit a differential signal (differential mode signal). However, the digitized and speeded up electronic devices are sensitive to stimulus from the outside. That is, in the case in which small abnormal voltage and a high frequency noise are introduced from the outside into an internal circuit of the electronic device, a circuit may be damaged and a signal may be distorted.
In order to prevent a circuit breakage or a signal distortion of electronic devices from occurring, a filter is mounted to interrupt the introduction of abnormal voltage and high frequency noise into a circuit. Generally, a common mode filter has been used in a high speed differential signal line, and the like, to remove a common mode noise.
The common mode noise is noise occurring at the differential signal line and the common mode filter removes noises that may not be removed by the existing EMI filter. The common mode filter contributes to improvement in EMI characteristics of a home appliance, and the like, and improvement of antenna characteristics of a cellular phone, and the like.
Referring to Japanese Patent Laid-Open Publication No. 2012-015494, a general common mode filter according to the related art has a structure in which a magnetic substrate is disposed at a lower part and an insulating layer enclosing a coil electrode is stacked thereon.
According to the above structure, one surface of the magnetic substrate and one surface of the insulating layer contact each other, forming an interface. Therefore, cracks or delaminating may frequently occur at the interface between the magnetic substrate and the insulating layer due to a difference in a material between the magnetic substrate and the insulating layer.
This is due to the bonding of heterogeneous materials having different chemical characteristics. When two members having different materials are bonded to each other, a thermal residual stress is concentrated on the bonded interface and the potential stress degrades the interlayer adhesion. Further, the contraction percentage may be different due to the difference in the thermal expansion coefficient during the firing process, such that the cracks or the delaminating may appear at the bonded interface.
The cracks or the delaminating occurring at the bonded interface may lead to facilitate the moisture permeation into the bonded interface from the outside, damage a product even by the small impact, and the like, thereby degrading the reliability of a product. Therefore, the common mode filter having excellent durability and the method of manufacturing the same are urgently needed.